(1) Field of the Invention
This invention relates to powder deposition machinery, and more particularly to a machine utilizable for applying a coating of plastic material originally in powdered form in a hopper, through a deposition apparatus and onto a shoe upper.
(2) Summary of the Prior Art
The shoe and apparel industry have for many years been applying stiffening and reinforcing means to their shoe uppers, blue jeans, pajamas, sports clothing, visors of caps and the like, and manufacturers have stitched, glued or otherwise applied layers of reinforcing material to their products for a variety of reasons. It has been standard for the shoe industry to apply the reinforcement/stiffening or decorative means as a layer of molten thermoplastic material adhereable to a shoe upper. Early attempts at reinforcing or stiffening a shoe upper have included providing preformed stiffener elements or counters, which are inserted into a shoe upper, prior to lasting. Separate moldable sheet materials softenable by heating or by solvent have been inserted into the shoe uppers prior to lasting and are shaped in the course of lasting to a desired configuration which configuration they retain by being allowed to harden before removal of the shoe upper from the last. Shoe uppers have been stiffened by impregnating a shoe component with a solution or dispersion in a volatile liquid vehicle of hardenable stiffener materials prior to lasting of the shoe upper, the shoe upper being stiffened by hardening of the impregnated material after the shoe is lasted.
A more recent arrangement for stiffening and or reinforcing shoe components or the like is shown in U.S. patent application Ser. No. 451,919, wherein a rotary deposition machine receives a powdered fusible material from a hopper and drops it through a conduit into a stencil apparatus. The powder is then drawn through the stencil and onto a rotatable receiving belt which carries the configuration of powder through an arcuate array of heating elements, finally into a join and cool station where a substrate such as a shoe upper or the like is pressed thereagainst, to withdraw the then fused configuration of powder from the rotatable belt. Sometimes, the powder in the hopper and/or the stencil will cake and not fall properly. A pneumatic "thumper" mechanism has been arranged on the stencil apparatus to free any caked powder therefrom.
The tubular conduit which leads to the stencil, from the hopper may accumulate the powder therein and prevent a proper discharge of the powder into the stencil apparatus.
It is an object of the present invention to provide an arrangement for keeping the conduit free of accumulated powder.
It is a further object of the present invention to keep the powder in the hopper in a proper state and enable the hopper to discharge its powder into the conduit in a desired granular state.